I'm not saying that working 8 hours a day necessarily is a problem. If you manage to keep that up having 8 hours of quality working time per day is great.

The problem lies in having a rigorous schedule telling you when and where to work. Another problem is fake work ( http://lifehacker.com/5710930/cut-out-the-fake-work-and-focu... ). In corporate environments there's a widespread tendency of wasting time on useless action just to pretend that there's work going on. Work also tends to fill up the time available for it ( http://en.wikipedia.org/wiki/Parkinsons_law ).

Activity more often than not is valued higher than efficiency or actually accomplishing something. This is why we see things like prolonged meetings and convoluted specification documents nobody actually reads. You didn't actually accomplish something but hey there's this 200 pages long bullshit specification that proves you've been working, right?

I think is due to our society's perception of what constitutes work. Work is seen as something that has to be hard, long and cumbersome or in other words: "If it doesn't suck it can't be work." People like the notorious Tim Ferriss who seemingly manage to get through work and live much more easily generally are regarded with suspicion.

So, while I think that the 4 hour work week maybe is a little extreme and certainly isn't applicable for everyone it shows the right direction. Work and work organization has to adapt in order to produce meaningful results, not just unhappy, stressed out workers.